Krill is a small crustacean which lives in all the major oceans world-wide. For example, it can be found in the Pacific Ocean (Euphausia pacifica), in the Northern Atlantic (Meganyctiphanes norvegica) and in the Southern Ocean off the coast of Antarctica (Euphausia superba). Krill is a key species in the ocean as it is the food source for many animals such as fish, birds, sharks and whales. Krill can be found in large quantities in the ocean and the total biomass of Antarctic krill (E. superba) is estimated to be in the range of 300-500 million metric tons. Antarctic krill feeds on phytoplankton during the short Antarctic summer. During winter, however, its food supply is limited to ice algae, bacteria, marine detritus as well as depleting body protein for energy. Virtue et al., Mar. Biol. (1996) 126, 521-527. For this reason, the nutritional values of krill vary during the season and to some extent annually. Phleger et al., Comp. Biochem. Physiol. 131B (2002) 733.
The long-chain omega-3 polyunsaturated fatty acids DHA and EPA are popularly called omega-3. Supplementary intake of omega-3 is recommended in the western world, due to generally low dietary intake and omega-3's health-promoting benefits. Benefits attributed to omega-3 include reduced risk and improved treatment outcomes regarding cardiovascular disease and inflammatory joint diseases. Better brain and central nervous system development, improved cognitive functioning, and improved skin health are additional benefits. Research indicates that even more omega-3 benefits for individuals will be identified and that greater intake can lead to better general health in western, industrialized cultures.
The omega-3 in krill oil is mainly in the omega-3 phospholipid form, which research suggests is a preferred dietary supplement when compared to omega-3 in triglyceride form. Marine omega-3 in dietary supplements is mostly derived from fish, such as fish body oil and cod liver oil, which provide omega-3 in triglyceride form. The omega-3 obtained from eating fatty fish such as salmon also provides some omega-3 in the phospholipid form.